1. Field of the Invention
The present invention relates to earth moving and excavating equipment. More particularly, the invention relates to road maintenance equipment adapted to clear and cut road shoulders and drainage ditches.
2. Description of the Prior Art
Sparsely traveled rural and logging roads are constructed with a minimum of roadbed packing and preparation. To protect the center crown of such roads from washouts by heavy rains and flood water, it is necessary to ditch such roads along both sides with shallow drainage trenches. These trenches ease the drainage course from under the road-bed crown and tend to prevent water saturation of the road-bed in the load bearing area.
In flat, low-lying areas, having considerable rainfall, road drainage ditches hold standing water throughout much of the year. High water tables and the absence of elevational fall are the dominate obstacles to sufficient road drainage in such areas. However, siltage washed from the road and surroundings aggravate natural drainage obstacles by filling and blocking the road ditches. To keep such roads serviceable, it is necessary to periodically recut the ditches and scrape the excavated material back upon the road crown.
Road building and maintenance arts have traditionally relied upon grading machinery to cut and maintain road drainage ditches. Such machinery is constructed and used as either self-powered or towed vehicles; usually having four to six wheel support points for a horizontal quadrant mounted scraper blade. From the central quadrant, a scraper blade usually is constructed to extend unsupported eight to ten feet in each lateral direction. When used for cutting road drainage ditches, it is at the outer ends of the blade that the greatest load is imposed on the equipment i.e. the greatest load is imposed at the weakest structural point.
Motor graders of traditional design are being driven by traction wheels running in the ditch being cut. If the ditch soil is water saturated, poor traction and sinking results.
Towed graders of traditional design have the same problem translated to the tractor vehicle. Additionally, two operators are required for the unit operation: one for the tractor and one for the grader. Considerable teamwork skill between the two operators is necessary for safe and adequate performance.
It is therefore, an object of the present invention to teach the construction and design of a towed vehicle specifically suited for road ditching and shoulder grading.
Another object of the present invention is to teach the construction of a towed ditch maintainer that requires no separate operator for the maintainer.
Another object of the present invention is to teach the design and construction of a road ditching machine having maximal structural strength concentrated at the greatest loading point.
Another object of the present invention is to teach the design and construction of a towed ditching machine that permits the powered tractor vehicle to run in an offset track closer to the road crown center and out of the ditch trench.